This invention relates to physical vapor deposition targets, to conductive integrated circuit metal alloy interconnections, and to electroplating anodes.
Aluminum and its alloys are common metal materials used in metal interconnects in the fabrication of integrated circuitry on semiconductor wafers. Yet as circuitry density increases and operating speed increases, aluminum""s electrical resistance is expected to prevent its use in many next generation circuits. Copper has been proposed as a strong candidate to replace aluminum and its alloys due to copper""s low bulk resistivity of 1.7 microohms.cm at near 100% purity (i.e., greater than 99.999% copper). Further, it has electromigration resistance compared to that of aluminum and its alloys of about 10 times or greater.
One problem associated with pure copper interconnects concerns abnormal grain growth or thermal stability in the deposited film. Further, such abnormal and undesired grain growth can reduce the film""s electromigration resistance. Low thermal stability is defined as, and abnormal grain growth is characterized by, a tendency of the individual crystal grains within copper to grow when exposed to a certain temperature. The higher the temperature at which a material recrystallizes or starts to grow larger grains, the higher the thermal stability of the material.
Elemental copper and its alloys can be deposited in integrated circuitry fabrication using a number of techniques, including chemical vapor deposition, physical vapor deposition and electrochemical deposition, such as electroplating. Ideally when deposited, the copper comprising sputtering target will have substantially uniform microstructure, a fine grain size, and preferred crystal orientation in order to achieve desired sputtering performance and resultant thin film formation and properties.
The invention includes conductive integrated circuit metal alloy interconnections, physical vapor deposition targets and electroplating anodes. In one implementation, a physical vapor deposition target includes an alloy of copper and silver, with the silver being present in the alloy at from less than 1.0 at % to 0.001 at %. In one implementation, a physical vapor deposition target includes an alloy of copper and silver, with the silver being present in the alloy at from 50 at % to 70 at %. In one implementation, a physical vapor deposition target includes an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
In one implementation, a conductive integrated circuit metal alloy interconnection includes an alloy of copper and silver, with the silver being present in the alloy at from less than 1.0 at % to 0.001 at %. In one implementation, a conductive integrated circuit metal alloy interconnection includes an alloy of copper and silver, with the silver being present in the alloy at from 50 at % to 70 at %. In one implementation, a conductive integrated circuit metal alloy interconnection includes an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
In one implementation, an electroplating anode includes an alloy of copper and silver, with the silver being present in the alloy at from less than 1.0 at % to 0.001 at %. In one implementation, an electroplating anode includes an alloy of copper and silver, with the silver being present in the alloy at from 50 at % to 70 at %. In one implementation, an electroplating anode includes an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
In other implementations, other useable copper alloys in physical vapor deposition targets, conductive integrated circuit metal alloy interconnections, and electroplating anodes include an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, Te, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Ti, and Pb. An electroplating anode is formed to comprise one or more of the above alloys.
In other implementations, the invention contemplates metal alloys for use as a conductive interconnection in an integrated circuit.